The present invention relates to a control system for steering a vehicle in which only front wheels are steerable or all wheels are steerable.
In a conventional vehicle having only a mechanical steering linkage, front wheels are steered in accordance with an angular displacement of a steering wheel (steering input quantity), and a dynamical variable such as yaw rate responsive to steering input is determined uniformly by a mechanical construction of the vehicle. Therefore, cornering characteristics are fixed according to a type of vehicle. It is practically impossible to endow a vehicle of a sedan type with characteristics of a sports car type without changing a vehicle construction drastically.
A competition car (rally car) is required to have superior accelerating ability and superior steering response simultaneously. However, these two requirements are incompatible because improvement of accelerating ability by increasing engine displacement unavoidably deteriorates steering response by increasing vehicle weight.
Furthermore, the cornering characteristics of a vehicle are changed when tire properties are changed by tire wear or tire change, or when the road surface condition changes.